212 HYMENOPTERA. 



Galls are often found on the blackberry, tenanted by another 

 genus, Diasti-ophus, which has usually fifteen-jointed antennae 

 in the male, and one joint less in the female. On opening a 

 gall containing this fl}', we often find an inquiline gall-fly, 

 Aulax, "showing the most striking resemblance in size, color- 

 ing and sculpture, to the Diastrophus, their companion. The 

 one is the very counterpart of the other, hardly showing any 

 differences, except the strictly generic characters." (Osten 

 Sacken.) These galls are also infested by Chalcid parasites, 

 Callimome (two species), Ormyrus, and Eurytoma. 



Osten Sacken enumerates "eight C3'nipidous galls on the dif- 

 ferent kinds of roses of this country." The flies all belong to 

 the genus Rhodites^ which is distinguished by the under side 

 of the last abdominal segment being drawn out into a long 

 point, while the antenniB are fourteen-jointed 

 in both sexes. R. toscb produces the bede- 

 guar gall ("from the Hebrew hedcguacJi^ said 

 to mean rose-apple"). It was formerlj' used 

 as a medicine. The galls form a moss-like 

 mass, encircling the rose branch. Rliodites 

 dichlocerus of Harris (Fig. 143), produces 

 hard, woody, irregular swellings of the branches. 



We now come to the second section, the Guest gall-flies (In- 

 quiliuETe), which are unable to produce galls themselves, as they 

 do not secrete the gall-producing poison, though possessing 

 a well developed ovipositor. Hence, like the Nomada, etc., 

 among bees, they are Cuckoo-flies, laying their eggs in galls 

 already formed. 



This group may generally, according to Mr. Walsh, be dis- 

 tinguished from the preceding by the sheaths of the ovipositor 

 always projecting, more or less, beyond the "dorsal "\alvc," 

 v/hicli is a small, hairy tubercle at the top of the seventh ab- 

 dominal segment. This dorsal valve also projects greatly. 

 In almost all the species, the ovipositor projects from between 

 the tips of the sheaths. 



Among the Inquiline genera are Sifnophnis, A7nbIynotus, 

 jSynerges, and Aulax, which are guests of various species of 

 Cynipides. 



In Ftgites and allies (Figitidae) , the third section of the 



